title: Effect of reciprocating file motion on microcrack formation in root canals: an SEM study.
abstract: OBJECTIVE
  To compare dentinal microcrack formation whilst using Ni-Ti hand K-files, ProTaper hand and rotary files and the WaveOne reciprocating file.
  
  
  METHODS
  One hundred and fifty mandibular first molars were selected. Thirty teeth were left unprepared and served as controls, and the remaining 120 teeth were divided into four groups. Ni-Ti hand K-files, ProTaper hand files, ProTaper rotary files and WaveOne Primary reciprocating files were used to prepare the mesial canals. Roots were then sectioned 3, 6 and 9 mm from the apex, and the cut surface was observed under scanning electron microscope (SEM) and checked for the presence of dentinal microcracks.
  
  
  RESULTS
  The control and Ni-Ti hand K-files groups were not associated with microcracks. In roots prepared with ProTaper hand files, ProTaper rotary files and WaveOne Primary reciprocating files, dentinal microcracks were present. There was a significant difference between control/Ni-Ti hand K-files group and ProTaper hand files/ProTaper rotary files/WaveOne Primary reciprocating file group (P < 0.001) with ProTaper rotary files producing the most microcracks. No significant difference was observed between teeth prepared with ProTaper hand files and WaveOne Primary reciprocating files.
  
  
  CONCLUSIONS
  ProTaper rotary files were associated with significantly more microcracks than ProTaper hand files and WaveOne Primary reciprocating files. Ni-Ti hand K-files did not produce microcracks at any levels inside the root canals.
authors.affiliation: Department of Conservative Dentistry and Endodontics, Meenakshi Ammal Dental College and Hospital, Meenakshi University, Maduravoyal, Chennai, Tamil Nadu, India.
authors.forename: V
authors.initials: V
authors.lastname: Ashwinkumar
authors.forename: J
authors.initials: J
authors.lastname: Krithikadatta
authors.forename: S
authors.initials: S
authors.lastname: Surendran
authors.forename: N
authors.initials: N
authors.lastname: Velmurugan
mesh_terms: D003786:Dental Pulp Cavity; D006801:Humans; D008855:Microscopy, Electron, Scanning
keywords: dentinal microcracks; protaper files; vertical root fracture; waveone reciprocating file